The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-219321 filed on Jul. 19, 2001 the entire contents thereof is hereby incorporated by reference.
1. Field of the Invention
This invention relates to a turbocharger arrangement structure for a personal watercraft.
2. Description of Background Art
While the power source in widespread personal watercrafts conventionally is a 2-cycle engine, it has been considered to use a 4-cycle engine for the power source in order to cope with a reduction in pollution in recent years.
However, since the output power of the 4-cycle engine is lower than that of the 2-cycle engine of the same total stroke volume, it is examined to incorporate an engine with a turbocharger in order to make up the power. The assignee of the present invention has proposed a personal watercraft in which an engine with a turbocharger is incorporated as disclosed in Japanese Patent Laid-Open No. 2001-140641.
In this personal watercraft, a 4-cycle engine 2 with a turbocharger 3 is incorporated inside of a body 1 as shown in FIGS. 11 and 12.
As shown also in FIGS. 13 and 14, an exhaust manifold 4 is provided on the left side of the 4-cycle engine 2 in an advancing direction F of the body 1. An intake chamber 5 is provided on the right side of the 4-cycle engine 2.
Exhaust gas from an exhaust gas exit 4a of the exhaust manifold 4 is introduced into a turbine portion 3T of the turbocharger 3, and compressed air from a compressor portion 3C of the turbocharger 3 is supplied into the intake chamber 5 described above through an intercooler 6.
In such a personal watercraft as described above, in order to make it difficult for water to enter a body 1, it is necessary to form a hull 1a (refer to FIG. 11) and a deck 1b to be watertight and to close an opening in the deck with a lid member (for example, a seat 7) to form an internal body space 1c. 
Meanwhile, in order to ensure intake of air into an engine 2, it is necessary to introduce atmospheric air from outside the body into the body internal space 1c. In a personal watercraft wherein a turbocharger is provided for an engine, when the atmospheric air outside the body is introduced into the body internal space 1c during operation of the personal watercraft, air is sometimes introduced together with water (for example, in the form of droplets) into the body. If the turbocharger is exposed to the water, then a casing and so forth of the turbocharger whose temperature is high is cooled suddenly and partially, which gives rise to disadvantages such as thermal fatigue that is liable to occur with the turbocharger.
The object of the present invention resides in a solution of such a problem as described above to provide a turbocharger arrangement structure for a personal watercraft which makes the turbocharger less liable to be exposed to water.
In order to attain the object described above, according to the present invention, a turbocharger arrangement structure for a personal watercraft includes a hull and a deck of the personal watercraft that are formed to be watertight and an opening of the deck that is closed up with a lid member to form a body internal space. An intake duct for introducing the atmospheric air outside the body is provided in the space while an engine and a turbocharger connected to an exhaust manifold of the engine are provided in the space and the turbocharger is disposed to be higher than a body internal opening of the intake duct.
According to the present invention, the turbocharger arrangement structure for a personal watercraft according to the present invention provides a water jacket that is formed in a casing of a turbine portion of the turbocharger and an oil jacket that is formed in a bearing casing of the turbocharger, and cooling water is supplied to the water jacket and cooling oil is supplied to the oil jacket.
According to the present invention, the turbocharger arrangement structure for a personal watercraft according to the present invention provides the cooling water to the water jacket that is supplied by a different turbocharger cooling water passage independent of any other cooling water passage.
With the turbocharger arrangement structure for a personal watercraft according to the present invention, the hull and the deck of the personal watercraft are formed to be watertight and the opening of the deck is closed up with the lid member to form the body internal space. The intake ducts for introducing the atmospheric air outside the body are provided in the space and the engine and the turbocharger are connected to the exhaust manifold of the engine and are provided in the space. The turbocharger is disposed to be higher than the body internal openings of the intake ducts. Therefore, when the atmospheric air outside the body is introduced into the body internal space through the intake ducts during operation of the personal watercraft, even if air is introduced together with water (for example, in the form of droplets), such a situation wherein the turbocharger becomes wet directly with the water becomes less likely to occur.
Accordingly, a situation wherein the casing and so forth of the turbocharger, whose temperature is high, are cooled suddenly and partially becomes less likely to occur. Thus thermal fatigue becomes less likely to occur with the turbocharger. As a result, the durability of the turbocharger is augmented.
The turbocharger arrangement structure for a personal watercraft according to the present invention provides a water jacket that is formed in the casing of the turbine portion of the turbocharge and the oil jacket is formed in the bearing casing for the turbocharger. Cooling water is supplied to the water jacket and cooling oil is supplied to the oil jacket. Consequently, such a situation wherein the temperature of the turbocharger becomes excessively high is eliminated.
Accordingly, when the atmospheric air outside the body is introduced into the body internal space through the intake ducts during operation of the personal watercraft, even if air is introduced together with water (for example, in the form of droplets) and the turbocharger becomes exposed to the water, the temperature variation of the casing of the turbocharger by the water is suppressed to be small.
As a result, thermal fatigue becomes less likely to occur with the turbocharger, and the durability of the turbocharger is augmented with certainty.
With the turbocharger arrangement structure for a personal watercraft according to the present invention, cooling water for the water jacket is supplied through the different turbocharger cooling water passages independent of the other cooling water passages. Thus, the turbocharger is cooled efficiently.
Accordingly, when the atmospheric air outside the body is introduced into the body internal space through the intake ducts during operation of the personal watercraft, even if air is introduced together with water (for example, in the form of droplets) and the turbocharger is exposed to the water, the temperature variation of the casing of the turbocharger by the water is suppressed smaller.
As a result, thermal fatigue becomes further less likely to occur with the turbocharger, and the durability of the turbocharger is augmented with a higher degree of certainty.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.